Electronic structure of cubic Li(Fe0.1Mn1.9)O4 studied with Mössbauer spectroscopy and first-principles calculation

Mossbauer spectrum was collected in Fe3+ doped cubic LiMn2O4 (LiFe0.1Mn1.9O4) by using 57Fe as the radiation source. In the model of the crystal-field theory, the energy gaps between different d orbitals, ΔE(b1g−a1g) and ΔE(b2g−eg), characterize the strength of the Jahn–Teller effect in the crystal. A relationship between the Mossbauer quardrupole splitting and the energy gaps was established, based on which both ΔE(b1g−a1g) and ΔE(b2g−eg) of the [MnO6] octahedron in LiFe0.1Mn1.9O4 are estimated to be about 0.41 and 0.30 eV, respectively. Electronic structure of LiMn2O4 was studied theoretically via ab initio calculation based on the density-functional theory. Calculation shows that a gap about 0.28 eV between the filled Mn d bands is equivalent to ΔE(b2g−eg). It also shows that the first unoccupied states are dominated by Mn 3d contribution essentially from both a1g and b1g of Mn d states. Distance between the two peaks in the first unoccupied band was used to calculate ΔE(b1g−a1g), which is about 0.36 e...